The third early-19th-century outing for British agent Captain John Valcourt Justice--this time looking into a nautical mystery that just might have connections to the Napoleonic Wars circa 1807. A Danish vessel, the Oden, has disappeared somewhere between Copenhagen and Portsmouth; oddly, however, as Justice's friend from Lloyd's of London confides, no insurance claim has been filed! What's going on? So wonders the insurance company; so, too, wonders Justice's higher-up at the clandestine Board of Beacons, Bells, Buoys, and Mercantile Messengers. Justice is soon on his way to French-occupied Europe, then, together with longtime sidekick Scorcher and a secret weapon: a James Bond-style snuffbox engineered to explode in an enemy's face. In Holland they find that their informer has already been murdered--and that the Oden has been sneakily harbored and re-named. The explanation? Justice quickly realizes that supposedly neutral Denmark is secretly conniving to turn over its super-fleet to Napoleon: the government itself is inactive, perhaps, but a group of anti-English Danish super-patriots has been allowed to make nasty underground deals with the French. Onward, then, to Copenhagen via Hamburg--to learn the secret plans for the Danish fleet (leading to an invasion of England!) and, if possible, to foil them. Along the way, Justice goes into hand-to-hand combat against assorted French and Danish villains. He falls for a Danish shipbuilder's wife--even though she seems to be connected to those Danish super-patriots. There are several murders, several traitors in friends' clothing, canal chases. . . and, finally, Justice's participation in the English invasion of Denmark, which he has helped to make possible. A bit talky, a little humorless, and Justice is faceless--but, as before, ""Forrest"" (a.k.a. Norman MacKenzie and Anthony Brown) offers more historical substance than most period alerting-doers, along with solid portions of action and scenery.